THIN PROFILE CONDUCTOR ASSEMBLY FOR MEDICAL DEVICE LEADS
A medical device lead includes a thin profile conductor assembly. A proximal connector includes a proximal end that is configured to couple the lead to a pulse generator. An insulative lead body extends distally from the proximal connector. The conductor assembly extends distally from the proximal end within the lead body and includes a non-conductive tubular core member that defines a lumen, an outer insulative layer, and a multilayer conductor between the tubular core member and the outer insulative layer. The multilayer conductor is electrically connected to the proximal connector and includes a first conductive layer adjacent to the tubular core member and a second conductive layer adjacent to the first conductive layer opposite the tubular core member. A conductivity of the second conductive layer is greater than a conductivity of the first conductive layer.
This application claims priority to Provisional Application No. 61/159,572, filed Mar. 12, 2009, which is herein incorporated by reference in its entirety.
TECHNICAL FIELDThe present invention relates to implantable medical devices. More particularly, the present invention relates to configurations and methods of manufacture for thin profile conductive assemblies for medical device leads.
BACKGROUNDImplantable medical devices for treating a variety of medical conditions with electrical stimuli are well known. Implantable medical devices generally include a medical electrical lead for delivering an electrical stimulus to a targeted site within a patient's body such as, for example, a patient's heart or nervous system. Such leads generally have an elongated, flexible insulating body, one or more inner conductors extending through lumens formed in the body and one or more exposed electrodes connected to the distal ends of the conductors.
Leads may be introduced into the patient's vasculature at a venous access site and transvenously guided through veins to the sites where the lead electrodes will be implanted or otherwise contact tissue at the targeted therapy site. A pulse generator attached to the proximal ends of the conductors delivers an electrical stimulus therapy to the targeted site via the one or more conductors.
SUMMARYDiscussed herein are various conductor assemblies for implantable medical electrical leads including conductive layers having differing electrical conductivities, as well as medical electrical leads including such conductor assemblies.
In Example 1, a medical device lead includes a proximal connector having a proximal end and configured to couple the lead to a pulse generator, an insulative lead body extending distally from the proximal connector, and a conductor assembly extending distally from the proximal end within the lead body. The conductor assembly includes a non-conductive tubular core member that defines a lumen, an outer insulative layer, and a multilayer conductor between the tubular core member and the outer insulative layer. The multilayer conductor is electrically connected to the proximal connector and includes a first conductive layer adjacent the tubular core member and a second conductive layer adjacent the first conductive layer opposite the tubular core member. A conductivity of the second conductive layer is greater than a conductivity of the first conductive layer.
In Example 2, the medical device lead according to Example 1, wherein a thickness of the first conductive layer in a dimension extending between the tubular core member and the outer insulative layer is less than a thickness of the second conductive layer.
In Example 3, the medical device lead according to either Example 1 or 2, wherein the thickness of the first conductive layer is in the range of about 10 to about 30 nm and the thickness of the second conductive layer is in the range of about 0.2 to about 2 μm.
In Example 4, the medical device lead according to any of Examples 1-3, wherein the first conductive layer is comprised of a paramagnetic material and the second conductive layer is comprised of a diamagnetic material.
In Example 5, the medical device lead according to any of Examples 1-4, wherein the first conductive layer is comprised of Ti, and the second conductive layer is comprised of a material selected from the group consisting of Ag, Al, Au, and Pt.
According to Example 6, a method for making a conductive assembly for a medical electrical lead includes masking a non-conductive tubular core member with a pattern. The tubular core member defines a lumen. The method also includes depositing a first conductive layer on the masked tubular core member, and depositing a second conductive layer on the first conductive layer. The second conductive layer has a conductivity greater than the first conductive layer. The method further includes removing the mask from the tubular core member such that portions of the first conductive layer and the second conductive layer deposited on the mask are removed with the mask and a first conductive pattern remains on the tubular core member. The method further includes covering the tubular core member and the first conductive pattern with a first insulative layer.
In Example 7, the method according to Example 6, wherein masking the tubular core member with the pattern comprises spinning a fibrous material over the tubular core member.
In Example 8, the method according to either Example 6 or 7, wherein the first conductive layer is deposited on the masked tube via plasma enhanced chemical vapor deposition (PECVD).
In Example 9, the method according to any of Examples 6-8, wherein the second conductive layer is deposited on the first conductive layer via physical vapor deposition (PVD).
In Example 10, the method according to any of Examples 6-9, wherein the second conductive layer is deposited on the first conductive layer via galvanic deposition.
In Example 11, the method according to any of Examples 6-10, wherein a thickness of the first conductive layer in a dimension extending between the tubular core member and the outer insulative layer is less than a thickness of the second conductive layer.
In Example 12, the method according to any of Examples 6-11, wherein the first conductive layer is comprised of a paramagnetic material and the second conductive layer is comprised of a diamagnetic material.
In Example 13, the method according to any of Examples 6-12, wherein the tubular core member is covered with the first insulative layer via any of spray coating, dip coating, pulsed laser deposition, or condensation.
In Example 14, the method according to any of Examples 6-13, wherein the tubular core member and the first insulative layer are comprised of a polymer.
In Example 15, the method according to any of Examples 6-14, and further comprising (a) masking the first insulative layer with a pattern, (b) depositing a third conductive layer on the masked first insulative layer, (c) depositing a fourth conductive layer on the third conductive layer, wherein the fourth conductive layer has a conductivity greater than the third conductive layer, (d) removing the mask from the first insulative layer such that portions of the third conductive layer and the fourth conductive layer deposited on the mask are removed with the mask and a second conductive pattern remains on the first insulative layer, and (e) covering the first insulative layer and the second conductive pattern with a second insulative layer.
According to Example 16, a conductor assembly for a medical device lead includes a non-conductive tubular core member having a lumen, and an outer insulative layer is disposed about the non-conductive tubular core member. A multilayer conductor is between the tubular core member and the outer insulative layer. The multilayer conductor defines a conductor pattern and includes a first conductive layer adjacent to the tubular core member and a second conductive layer adjacent to the first conductive layer opposite the tubular core member. A conductivity of the second conductive layer is greater than a conductivity of the first conductive layer.
In Example 17, the conductor assembly according to Example 16, wherein a thickness of the first conductive layer in a dimension extending between the tubular core member and the outer insulative layer is less than a thickness of the second conductive layer.
In Example 18, the conductor assembly according to either Example 16 or 17, wherein the thickness of the first conductive layer is in the range of about 10 to about 30 nm and the thickness of the second conductive layer is in the range of about 0.2 to about 2 μm.
In Example 19, the conductor assembly according to any of Examples 16-18, wherein the first conductive layer is comprised of a paramagnetic material and the second conductive layer is comprised of a diamagnetic material.
In Example 20, the conductor assembly according to any of Examples 16-19, wherein the conductor pattern is helical.
In Example 21, the conductor assembly according to any of Examples 16-20, wherein turns of the helical pattern have a varying pitch along a major dimension of the conductor assembly.
In Example 22, the conductor assembly according to any of Examples 16-21, wherein the conductor pattern comprises a plurality of longitudinally extending conductive filars.
In Example 23, the conductor assembly according to any of Examples 16-22, wherein each of the longitudinally extending conductive filars is substantially straight.
In Example 24, the conductor assembly according to any of Examples 16-23, wherein each of the longitudinally extending conductive filars is undulating.
In Example 25, the conductor assembly according to any of Examples 16-24, wherein each of the longitudinally extending conductive filars is serpentine.
In Example 26, the conductor assembly according to any of Examples 16-25, wherein the multilayer conductor defines more than one conductive path.
While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.
While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
DETAILED DESCRIPTIONAs shown in
Although the illustrative embodiment depicts only a single implanted lead 14, it should be understood that multiple leads can be utilized so as to electrically stimulate other areas of the heart 20. In some embodiments, for example, the distal end of a second lead (not shown) may be implanted in the right atrium 22, and/or the distal end of a third lead (not shown) may be implanted in the right ventricle 24. Other types of leads such as epicardial leads may also be utilized in addition to, or in lieu of, the lead 14 depicted in
During operation, the lead 14 can be configured to convey electrical signals between the IMD 12 and the heart 20. For example, in those embodiments where the IMD 12 is a pacemaker, the lead 14 can be utilized to deliver electrical stimuli for pacing the heart 20. In those embodiments where the IMD 12 is an implantable cardiac defibrillator, the lead 14 can be utilized to deliver electric shocks to the heart 20 in response to an event such as a heart attack or arrhythmia. In some embodiments, the IMD 12 includes both pacing and defibrillation capabilities.
The electrical signals are carried between the IMD 12 and electrodes at the distal end 18 by one or more conductors extending through the lead 14. The one or more conductors are electrically coupled to a connector suitable for interfacing with the IMD 12 at the proximal end 16 of the lead 14, and to one or more electrodes at the distal end 18. According to the present invention, the one or more conductors have a low profile (i.e., the distance from the center to the outer surface of the lead 14) to minimize the diameter of the lead 14. In addition, the one or more conductors are configured to impart flexibility to the lead 14 to facilitate traversal of tortuous vascular passages during implantation of the lead 14. Also, in some embodiments, the one or more conductors are configured to minimize effects of magnetic resonance imaging (MRI) scans on the functionality and operation of the lead 14. For example, in certain embodiments, the one or more conductors are configured to dissipate electromagnetic energy received by the lead 14 during an MRI scan.
The inner core layer 52 defines a lumen 58 through the shaft assembly 50. In some embodiments, the lumen 58 is sized and shaped to receive a guide wire or stylet employed during implantation of the lead 14. The inner core layer 52 is comprised of a flexible, non-conductive material. In some embodiments, the inner core layer 52 is comprised of a polymeric material, such as polypropylene, polyamide, polyethylene, or polyurethane.
The inner conductor 54 may include one or more layers of conductive material that are deposited onto the inner core layer 52. The conductive material may be deposited using a variety of techniques including, but not limited to, plasma enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD), or galvanic deposition. The materials used for the inner conductor 54 may be selected to provide good conductivity as well as good adherence to the inner core layer 52. In some embodiments, a thin seed layer is deposited adjacent the inner core layer 52 and a thicker, high conductivity layer is deposited on the seed layer. In some embodiments, the seed layer is comprised of Ti and the high conductivity layer is comprised of Ag, Al, Au, or Pt. In other embodiments, the high conductivity layer is comprised of other materials, such as Nb, Ta, or Ti. The inner conductor 54 has a thickness tc extending between the inner core layer 52 and the outer insulative layer 56. In some embodiments, the total thickness tc of the inner conductor 54 is in the range of about 0.2 μm to about 2.0 μm. The thickness tc for the inner conductor 54 is less than the thickness of conventional lead conductors, providing for a lead with a lower profile and greater flexibility.
The cross-section of the inner conductor 54 may be fabricated to provide a desired impedance at the lead electrode or electrodes to which the inner conductor 54 is attached. In some embodiments, the cross-section of the inner conductor 54 is such that the impedance of each lead electrode is less than about 80 a For example, the impedance of each lead electrode may be in the range of about 20Ω to about 80Ω.
The outer insulative layer 56 is arranged over the inner conductor 54 to isolate the inner conductor 54 from the tissue adjacent to the lead 14. The outer insulative layer 56 is made of a flexible, highly durable, fatigue resistant, and bio-compatible insulative material. In some embodiments, the outer insulative layer 56 is comprised of a polymeric material, such as styrene isoprene butadiene (SIBS), polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), fluorinated ethylene propylene (FEP), ethylene-tetrafluoroethylene (ETFE), or another biocompatible polymer. In some embodiments, the outer insulative layer 56 is deposited over the inner conductor 54 using processes such as spray coating, dip coating, pulsed laser deposition (PLD), or condensation. The outer insulative layer 56 may alternatively be formed over the combined inner core layer 52 and inner conductor 54 by pulling the assembly through a tube of insulative material.
According to some embodiments, the inner conductor 54 is formed with certain characteristics to provide desired physical, electrical, and/or magnetic properties for the lead 14. For example, the conductive material of the inner conductor 54 may be patterned to minimize the effects of magnetic resonance imaging (MRI) fields on the performance and response of the lead 14. In some embodiments, the inner conductor 54 is patterned to have an inductance that prevents the MRI fields from heating the lead electrodes. In addition, the material or materials for the inner conductor 54 may be selected to provide distortion free imaging by minimizing image artifacts and voids around the lead 14. For example because the magnetization induced in a material when placed in a magnetic field is a function of the magnetic susceptibility of the material, conductive materials having a low magnetic susceptibility (e.g., similar to the magnetic susceptibility of water) may be used. The inner conductor 54 may also be patterned to provide a desired level of flexibility in the lead 14, or to provide increased or decreased flexibility in portions of the lead 14. Furthermore, in embodiments with multiple inner conductors, active electrical elements, such as capacitors and diode AC switches, may be integrated between the conductor paths to avoid coupling of the MRI field into the lead 14.
The conductive layer 106 may be deposited onto the base layer 104 in a variety of ways. In some embodiments, the conductive layer 106 is deposited via physical vapor deposition (PVD). In other embodiments, the conductive layer 106 is deposited via galvanic deposition. In further embodiments, the conductive layer 106 is deposited by sputtering, such as laser sputtering. In still further embodiments, the conductive layer 106 is deposited using other techniques suitable for coating the base layer 104 with the conductive layer 106.
It will be appreciated that the configuration for the inner conductor 54 is not limited to the helical pattern shown, and that the principles of the present invention may be applied to inner conductors 54 having other types of patterns. For example,
In certain applications, the lead 14 (
It will be appreciated that while two inner conductors 154 and 158 are shown in the embodiments of
In summary, the present invention relates to a medical device lead including a thin profile conductor assembly. A proximal connector includes a proximal end that is configured to couple the lead to a pulse generator. An insulative lead body extends distally from the proximal connector. The conductor assembly extends distally from the proximal end within the lead body and includes a non-conductive tubular core member that defines a lumen, an outer insulative layer, and a multilayer conductor between the tubular core member and the outer insulative layer. The multilayer conductor is electrically connected to the proximal connector and includes a first conductive layer adjacent to the tubular core member and a second conductive layer adjacent to the first conductive layer opposite the tubular core member. A conductivity of the second conductive layer is greater than a conductivity of the first conductive layer. A medical device lead conductor as described has a very low profile, providing leads having small diameters. In addition, the conductor is configured to impart increased flexibility to the lead to facilitate traversal of tortuous vascular passages during implantation of the lead. The conductor may also include features or configurations that make the lead suitable for magnetic resonance imaging (MRI) environments.
Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. While the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof. For example, while the deposited conductive material has been described with regard to the inner conductor(s) of a cardiac lead it will be appreciated that the principles of the present invention are applicable to other types of leads, such as neuromodulation leads, as well as other types of conductive coating applications, such as housings, flexible electrodes, and electromagnetic interference (EMI) shielding.
Claims
1. A medical device lead comprising:
- a proximal connector having a proximal end and configured to couple the lead to a pulse generator;
- an insulative lead body extending distally from the proximal connector;
- a conductor assembly extending distally from the proximal end within the lead body, the conductor assembly comprising a non-conductive tubular core member that defines a lumen, an outer insulative layer, and a multilayer conductor between the tubular core member and the outer insulative layer, wherein the multilayer conductor is electrically connected to the proximal connector and includes a first conductive layer adjacent the tubular core member and a second conductive layer adjacent the first conductive layer opposite the tubular core member, and wherein a conductivity of the second conductive layer is greater than a conductivity of the first conductive layer.
2. The medical device lead of claim 1, wherein a thickness of the first conductive layer in a dimension extending between the tubular core member and the outer insulative layer is less than a thickness of the second conductive layer.
3. The medical device lead of claim 2, wherein the thickness of the first conductive layer is in the range of about 10 to about 30 nm and the thickness of the second conductive layer is in the range of about 0.2 to about 2 μm.
4. The medical device lead of claim 1, wherein the first conductive layer is comprised of a paramagnetic material and the second conductive layer is comprised of a diamagnetic material.
5. The medical device lead of claim 4, wherein the first conductive layer is comprised of Ti, and the second conductive layer is comprised of a material selected from the group consisting of Ag, Al, Au, and Pt.
6. A method for making a conductive assembly for a medical electrical lead, the method comprising:
- masking a non-conductive tubular core member with a pattern, wherein the tubular core member defines a lumen;
- depositing a first conductive layer on the masked tubular core member;
- depositing a second conductive layer on the first conductive layer, wherein the second conductive layer has a conductivity greater than the first conductive layer;
- removing the mask from the tubular core member such that portions of the first conductive layer and the second conductive layer deposited on the mask are removed with the mask and a first conductive pattern remains on the tubular core member; and
- covering the tubular core member and the first conductive pattern with a first insulative layer.
7. The method of claim 6, wherein masking the tubular core member with the pattern comprises spinning a fibrous material over the tubular core member.
8. The method of claim 6, wherein the first conductive layer is deposited on the masked tube via plasma enhanced chemical vapor deposition (PECVD).
9. The method of claim 6, wherein the second conductive layer is deposited on the first conductive layer via physical vapor deposition (PVD).
10. The method of claim 6, wherein the second conductive layer is deposited on the first conductive layer via galvanic deposition.
11. The method of claim 6, wherein a thickness of the first conductive layer in a dimension extending between the tubular core member and the outer insulative layer is less than a thickness of the second conductive layer.
12. The method of claim 6, wherein the first conductive layer is comprised of a paramagnetic material and the second conductive layer is comprised of a diamagnetic material.
13. The method of claim 6, wherein the tubular core member is covered with the first insulative layer via any of spray coating, dip coating, pulsed laser deposition, or condensation.
14. The method of claim 6, wherein the tubular core member and the first insulative layer are comprised of a polymer.
15. The method of claim 6, and further comprising:
- masking the first insulative layer with a pattern;
- depositing a third conductive layer on the masked first insulative layer;
- depositing a fourth conductive layer on the third conductive layer, wherein the fourth conductive layer has a conductivity greater than the third conductive layer;
- removing the mask from the first insulative layer such that portions of the third conductive layer and the fourth conductive layer deposited on the mask are removed with the mask and a second conductive pattern remains on the first insulative layer; and
- covering the first insulative layer and the second conductive pattern with a second insulative layer.
16. A conductor assembly for a medical device lead, the conductor assembly comprising:
- a non-conductive tubular core member having a lumen;
- an outer insulative layer disposed about the non-conductive tubular core member; and
- a multilayer conductor between the tubular core member and the outer insulative layer, wherein the multilayer conductor defines a conductor pattern and includes a first conductive layer adjacent to the tubular core member and a second conductive layer adjacent to the first conductive layer opposite the tubular core member, and wherein a conductivity of the second conductive layer is greater than a conductivity of the first conductive layer.
17. The conductor assembly of claim 16, wherein a thickness of the first conductive layer in a dimension extending between the tubular core member and the outer insulative layer is less than a thickness of the second conductive layer.
18. The conductor assembly of claim 17, wherein the thickness of the first conductive layer is in the range of about 10 to about 30 nm and the thickness of the second conductive layer is in the range of about 0.2 to about 2 μm.
19. The conductor assembly of claim 16, wherein the first conductive layer is comprised of a paramagnetic material and the second conductive layer is comprised of a diamagnetic material.
20. The conductor assembly of claim 16, wherein the conductor pattern is helical.
21. The conductor assembly of claim 20, wherein turns of the helical pattern have a varying pitch along a major dimension of the conductor assembly.
22. The conductor assembly of claim 16, wherein the conductor pattern comprises a plurality of longitudinally extending conductive filars.
23. The conductor assembly of claim 22, wherein each of the longitudinally extending conductive filars is substantially straight.
24. The conductor assembly of claim 22, wherein each of the longitudinally extending conductive filars is undulating.
25. The conductor assembly of claim 22, wherein each of the longitudinally extending conductive filars is serpentine.
26. The conductor assembly of claim 16, wherein the multilayer conductor defines more than one conductive path.
Type: Application
Filed: Feb 12, 2010
Publication Date: Sep 16, 2010
Patent Grant number: 9084883
Inventor: Torsten Scheuermann (Munich)
Application Number: 12/704,939
International Classification: A61N 1/02 (20060101); H01B 7/00 (20060101); B05D 5/12 (20060101);